A couple of gust fronts earlier this evening produced a late round of showers/thunderstorms along the Continental Divide. Persistent easterly surface flow has this afternoon and evening has ushered in upper 40s to low 50s dew points across the District. A stronger upper-level disturbance is expected to move into the region tomorrow, however, these evening storms have the potential to tap into some of that energy, increasing the chance for storms into the late evening. Once storms start moving east, general movement speeds will be between 10-15mph from west to east. A few erratic motions could be possible if stronger storms are able to form along outflow boundaries. The best chance for storms will be over the next hour, through midnight tonight, with at least a LOW chance for Message 1s to be issued. The biggest threat this evening would be a quick 0.5” in 10-20 minutes as storms have the potential to tap into decent surface moisture.

STORM RAINFALL POTENTIAL AND DURATION: Typical showers and isolated thunderstorms will produce a 0.05-0.25” total in 10-30 minutes. A moderate to strong shower/thunderstorm will produce 0.25-0.75” total in 10-30 minutes.

WORST CASE SCENARIO: A strong, stationary thunderstorm, or training of thunderstorm cells will have the potential to produce up to 1.50” total in under 60 minutes.

A LOOK AHEAD: The heat wave begins to recede tomorrow with the arrival of a cold front and cutoff upper level low. Temperatures will reach the mid 80s, dew points in the 50s, and precipitable water (PWAT) values around 1.00”. These conditions support chances for scattered to widespread organized convection developing by the afternoon. A few storms may be capable of producing heavy rainfall across the District. Storms will quickly move northeast, exiting the area by the early evening.